The invention relates to a filler material for a thermal production of a joint or of a material layer metallically connected to the base material of or on objects of light metal and/or zinc alloys with a thermal conductivity of more than 110 W/mK, and to a method for producing the same with means for the preparation thereof in situ and/or storage. To improve the quality of the connection, it is provided according to the invention that the filler material is formed as unwindable filler wire, built up of a sheath optionally provided with a surface layer formed from polymer(s) and graphite and comprising aluminum and/or magnesium and/or zinc or a deformable alloy of these metals with a thermal conductivity of more than 110 W/mK and a core of compacted powder, whereby the core material comprises a metal powder and/or a powder of at least one metal compound and/or a non-metallic compound and/or an agent giving off gas at increased temperature and/or at least one component forming slag. The production is characterized by a filler wire production known per se, but with an optionally coated sheath of a ductile light metal or the like alloy, with a correctly positioned winding on coils and providing the same with a protection against moisture.